1. Field of the Invention
The present invention relates to a method of manufacture of a turnbuckle and, in particular, to an improved method for manufacturing a one piece turnbuckle.
2. Description of the Related Art
A conventional turnbuckle as appearing in FIG. 16 includes two cylindrical members 1 joined by two parallel bars 3 by welding at welding lines 4, with each of the cylindrical members 1 having a tapped portion 2 for engaging with bolts or with other structures which are intended to be retained by the turnbuckle. A drawback of the turnbuckle is that the cylindrical members 1 have a tendency to disengage from the parallel bars 3 at the welding lines 4 when the turnbuckle is subjected to a relatively big load. Therefore, a one piece seamless turnbuckle is disclosed in EP0,700,748 to overcome the problem.
Referring to EP0,700,748, the turnbuckle manufactured according to the method disclosed has overcome the problem and provided a better tensile strength. However, the manufacture of the turnbuckle is discovered to suffer a certain degree of difficulty relating to the fabrication of end portions.
There is a typical method for manufacturing a one piece turnbuckle that involves hot forging process. However, the forging usually requires expensive tooling and machines. Furthermore, the forging usually requires a bulky starting material, and the metal removal requirement is a necessity. Thus, the turnbuckle is heavy, expensive to manufacture, and material consuming.
The present invention is, therefore, intended to obviate or at least alleviate the problems encountered in the prior art.